This page lists common issues we came across when using Google Ad Manager on your site. They can happen whether you are using our Google Ad Manager Integration or placing the GAM tags manually.

Always wait 30 minutes

Changes made in your Google Ad Manager can take time until they are visible on your site. We find that only after 30 minutes you can be sure that your change should be visible on your site.

If you made a change on your site and not in your Google Ad Manager account then make sure to clear your website cache.

Re-using the same ad units

While the same ad units can be used multiple times on a page, you would need to make sure that the following is true:

  • Every creative can only be displayed once per page. If you want to deliver it multiple times, you would need to duplicate the creative multiple times in the line item and check out the next suggestion on this list.
  • By default, a line item only delivers one creative per page. If you have multiple ad units delivering ads from the line item, only one will show an ad. If you have multiple creatives in the same line item, you must set the option Adjust delivery > Display creatives in the line item’s settings to “As many as possible”.

Responsive AdSense ads are too small

When using Google AdSense ads through Google Ad Manager, the ads can be smaller than when placing the AdSense tags directly on your site. This happens because Google Ad Manager ad units have fixed sizes and don’t expand as dynamically as responsive AdSense ads do.

The solution is either to create bigger sizes of the Google Ad Manager ad units that contain the AdSense ads or place AdSense ads directly on your site.

Ad units are missing sizes

In most setups, ad units need to have sizes assigned in order to deliver ads. Go to Inventory > Ad units in your Google Ad Manager account and check if you find values in the Sizes column.

All sizes that could be visible on your website must also be attached to the ad unit’s code.

E.g., the following line of code from an ad unit could show a 728x90 leaderboard or 336x280 medium rectangle.

googletag.defineSlot('/1234567890/mixed-group', [[336, 280], [768, 90]], 'div-gpt-ad-987654321-0')

The next code is completely missing ad sizes. Maybe this happened because the code was manipulated, or the ad unit does not have sizes assigned in your Ad Manager account. Set up sizes and update the code to resolve it.

googletag.defineSlot('/1234567890/mixed-group', [], 'div-gpt-ad-987654321-0')

The following line would only deliver a leaderboard, since the size for the medium rectangle is missing in your code.

googletag.defineSlot('/1234567890/mixed-group', [768, 90], 'div-gpt-ad-987654321-0')

If you have set up the correct sizes in your Ad Manager account then you can just update the ad code on the ad edit page when using our Google Ad Manager integration.

The wrong ad sizes are visible

Check the following suggestions if your ad unit is set up with specific sizes, e.g., 300×250 and 468×60, but an ad with a bigger size is displayed on your site.

  • Open the Google Ad Manager debug mode by adding ?googfc to the URL.
  • Look for the ad with the wrong sizes

If the “Slot size” information returns the ad unit sizes you set up to being delivered then the issue is within the setup of your Ad Manager account. go through the line items and creative settings to find the cause.

Example of ad unit sizes.

If the Slot size information on your site is wrong then the problem is with the ad unit code on your site. A couple of common causes are:

  • a missing or wrong ad size in the ad unit code, see Ad units are missing sizes for more information
  • a missing or wrong information in the sizeMapping array
  • using sizeMapping with the same sizeMapping array assigned to different ad units

Ads are automatically stretched to fit the device

Google Ad Manager can extend certain ad types (currently display and out-stream video) to fit the full width of a device. E.g., it would scale a 300×250 ad to 360×300 on a device with a width of 360px. This is a feature, not a bug. You can learn more about it from their manual.